Optic Nerve Canal Variations and Their Surgical Implications: A Ct-based Study Using the Sagar Classification

Optic Nerve Canal Variations and Their Surgical Implications: A Ct-based Study Using the Sagar Classification | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Optic Nerve Canal Variations and Their Surgical Implications: A Ct-based Study Using the Sagar Classification Dr. MANWINDER SINGH, Dr. SALONY SHARMA, Dr. SANDEEP BANSAL, Dr. HARNEET SANDHU, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7654380/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract BACKGROUND: Anatomical variations in the optic nerve canal (ONC) significantly influence surgical risk during endoscopic procedures involving the posterior paranasal sinuses. This study evaluates ONC morphology using the Sagar classification via high-resolution computed tomography (CT), with clinical emphasis on predicting surgical vulnerabilities. MATERIALS AND METHODS: A prospective observational study was conducted over 12 months at a tertiary hospital in North India involving 75 adult patients diagnosed with chronic rhinosinusitis (CRS) according to EPOS 2020 criteria. Bilateral ONCs (N=150) were categorized into four types using CT scans and assessed for bony dehiscence, anterior clinoid process (ACP) pneumatization, and presence of Onodi cells. RESULTS: Type I ONCs were predominant (60%), followed by Type II (14.7%), Type III (13.3%), and Type IV (12%). Type III ONCs had the highest prevalence of bony dehiscence (50%) and ACP pneumatization (68.8%), indicating increased anatomical vulnerability. Onodi cells were seen in 32.7% of cases, further complicating surgical access. CONCLUSION: Detailed CT evaluation of ONC morphology is essential for individualized surgical planning. Type III ONCs, with their high-risk anatomical profile, require particular attention in preoperative imaging due to elevated risk of optic nerve injury. Optic nerve canal (ONC) CT imaging Sagar classification Endoscopic sinus surgery Bony dehiscence Anterior clinoid process pneumatization Onodi cells Chronic rhinosinusitis (CRS) Surgical anatomy Figures Figure 1 Figure 2 Figure 3 Figure 4 BACKGROUND The anatomical relationship between the optic nerve (ON) and the posterior paranasal sinuses—particularly the posterior ethmoid and sphenoid sinuses—is known to vary significantly. While the optic nerve canal (ONC) typically lies superolateral to the sphenoid sinus, it can occasionally protrude into or course through it entirely (shown in Figure 1 ) . In such cases, the nerve may be shielded only by a thin bone layer or mucosa, increasing its susceptibility to injury, especially when the bony wall is dehiscent or the sinus is extensively pneumatized. A key variant of surgical relevance is the Onodi cell, a posterior ethmoidal air cell that may extend laterally and superiorly, sometimes enveloping the optic nerve. The proximity of this cell to vital structures—including the optic chiasma, pituitary gland, olfactory tract, and cranial fossae—makes accurate anatomical mapping essential prior to endoscopic sinus procedures. The anterior wall of the sphenoid sinus commonly contains the sinus ostium and connects to the ethmoid and vomer bones medially, and to the lateral ethmoid mass bilaterally. Onodi cells can displace this wall in multiple directions, complicating the anatomy. The thin lateral walls of the sphenoid sinus, which contain critical structures such as the internal carotid artery (ICA), ON, and cavernous sinus, are divided into orbital and cranial zones. Due to the diversity in sphenoid and ethmoid sinus pneumatization, preoperative awareness of these variations is vital. Delano et al. (1996) proposed a classification system to clarify ON-sinus relationships, which was later refined as the “Sagar classification” in 2017 for improved surgical relevance. This study aims to evaluate the relationship between the optic nerve and the posterior paranasal sinuses through nasal endoscopy and non-contrast CT imaging (NCCT nose and PNS), using the Sagar classification as a framework. By identifying anatomical patterns, the research seeks to support safer surgical planning and reduce the risk of optic nerve injury during endoscopic interventions. MATERIALS AND METHODS Study Design and Setting This prospective observational study was conducted over a 12-month period within the Departments of Otorhinolaryngology and Radiology at Government Multispeciality Hospital, Sector 16, Chandigarh. Participants Adults (18–75 years) presenting to the ENT outpatient department with signs and symptoms consistent with chronic rhinosinusitis (CRS) were enrolled. CRS diagnosis adhered to EPOS 2020 criteria, requiring ≥2 symptoms lasting at least 12 weeks—major (nasal obstruction, nasal discharge) or minor (facial pain/pressure, hyposmia)—plus endoscopic or CT evidence of mucosal pathology. Inclusion criteria comprised: - Age between 18 and 75 years - Endoscopic findings of deviated nasal septum, septal spur, turbinate hypertrophy, or concha bullosa - Willingness to undergo CT imaging Exclusion criteria comprised: - Age <18 years - Congenital craniofacial anomalies - Sinonasal tumors or prior sinonasal surgery - Acute infection with nasal polyposis - Contraindications to ionizing radiation or significant comorbidities Sample Size and Sampling Seventy-five CRS patients were recruited via simple random sampling. Each participant underwent non-contrast CT scanning of the paranasal sinuses. Ethical Considerations The study protocol received approval from the Institutional Review Board of GMCH, Sector 32, Chandigarh. Written informed consent was obtained from all subjects before participation. Examiner Training and Calibration The radiologist underwent structured training on paranasal sinus anatomy and the Sagar classification of the optic nerve canal. Under expert supervision, the examiner interpreted CT scans in five pilot cases; intraobserver variability remained below 10%. Data Collection and Variables - Demographics: age, gender - Radiological parameters (via CT): - Anatomic variants (Onodi cells, pneumatisation of anterior clinoid process) - Optic nerve canal dehiscence - Optic nerve canal classification relative to the sphenoid and posterior ethmoid sinuses (Sagar classification)(TABLE 1) TABLE 1 TYPE OF ONC NUMBER OF CANALS BONY DEHISCENCE TYPE I Nerve courses immediately close to sphenoid sinus wall without indentation TYPE II Nerve courses close to the sphenoid sinus causing minimal indentation of the sinus wall TYPE III Nerve courses through the sphenoid sinus with at least 50% of the nerve being surrounded by air TYPE IV Nerve courses immediately adjacent to sphenoid and posterior ethmoid sinus ( presence of Onodi cell) The above variations are depicted in Figure 2,3 and 4. CT Imaging Protocol - Scanner: 16-slice Siemens Somatom Perspective - Parameters: 120 kV, 300 mAs, 0.8 mm slice thickness, 15 cm field of view - Acquisition: axial source images with coronal and sagittal reconstructions - Review: soft-tissue and bone windows assessed on multiplanar reformats to document paranasal sinus anatomy and optic nerve relationships. RESULTS The present study analysed 150 optic nerve canals (ONCs), obtained bilaterally from 75 individuals , using computed tomography (CT) to classify canal morphology based on the Sagar classification . The distribution, anatomical variations, and structural vulnerabilities associated with each ONC type were evaluated with respect to bony dehiscence and pneumatization of the anterior clinoid process (PAC) . Morphological Classification of ONCs The ONCs were categorized into four types—Type I to Type IV—based on their morphological characteristics. Of the 150 canals studied(TABLE 2): Type I was the most prevalent, comprising 60% of the sample (N=90), with a near-symmetrical distribution between right (29.3%) and left (30.7%) canals. Type II represented 14.7% (N=22) of canals, with slightly higher occurrence on the right side (9.4%) than the left (5.3%). Type III accounted for 13.3% (N=20), equally distributed across both sides. Type IV , the least common, comprised 12% (N=18), with marginal left-sided predominance (6.7% vs. 5.3%). The results demonstrate Type I morphology as the anatomical norm , with Types II–IV displaying greater variability and reduced prevalence. TABLE 2 : OPTIC NERVE CANAL TYPES DISTRIBUTION OF THE PATIENTS BASED ON SAGAR CLASSIFICATION ON CT SCAN TYPE OF ONC RIGHT LEFT TOTAL N % N % N % TYPE I 44 29.3 46 30.7 90 60 TYPE II 14 9.4 8 5.3 22 14.7 TYPE III 12 8 8 5.3 20 13.3 TYPE IV 8 5.3 10 6.7 18 12 Prevalence of Bony Dehiscence The integrity of the bony canal wall was assessed to identify cases of bony dehiscence , which may indicate structural vulnerability or pathological exposure of the optic nerve(TABLE 3): Type III canals showed the highest prevalence of dehiscence at 50% (10 out of 20 canals). Type II canals displayed a moderate rate of 25% (5 out of 22). Type IV had a dehiscence rate of 16.7% (3 out of 18). Type I demonstrated the lowest rate, with only 8.3% (7 out of 90) affected. The findings underscore a strong association between Type III morphology and increased susceptibility to bony dehiscence , implying a structurally compromised canal wall in nearly half of these cases. TABLE 3 : PREVALENCE OF BONY DEHISCENCE IN RESPECT TO ONC TYPES BASED ON CT SCAN TYPE OF ONC NUMBER OF CANALS BONY DEHISCENCE N % N % TYPE I 90 60 1 8.3 TYPE II 22 14.7 3 25 TYPE III 20 13.3 6 50 TYPE IV 18 12 2 16.7 Pneumatization of the Anterior Clinoid Process (PAC) Pneumatization of the anterior clinoid process, a variant anatomical feature with potential surgical implications, was assessed across ONC types (TABLE 4): Type III again emerged as the most susceptible, with 68.8% (11 out of 16 evaluated canals) showing PAC. Type II presented PAC in 18.7% of cases (3 out of 16 canals). Type IV exhibited PAC in 12.5% of canals (2 out of 16). Type I showed complete absence of PAC ( 0% ), indicating a consistently non-pneumatized structure. These results reveal a significant correlation between Type III ONC morphology and PAC , suggesting that this anatomical variant may serve as a predictive marker for complex canal anatomy. TABLE 4: PREVALENCE OF PNEUMATISATION OF ANTERIOR CLINOID IN RESPECT TO ONC TYPES BASED ON CT SCAN TYPE OF ONC NUMBER OF CANALS PNEUMATISATION OF ANTERIOR CLINOID PROCESS N % N % TYPE I 90 60 0 0 TYPE II 22 14.7 3 18,7 TYPE III 20 13.3 11 68.8 TYPE IV 18 12 2 16.7 DISCUSSION Endoscopic sinus and skull base surgeries necessitate precise anatomical knowledge due to the intimate relationship between the paranasal sinuses and critical neurovascular structures such as the optic nerve and internal carotid artery. Variations in optic canal morphology, pneumatization of surrounding bone, and the presence of ethmoidal cell variants substantially influence surgical access and risk profiles. Morphological Spectrum and Clinical Implications In the current study, 150 ONCs were evaluated using high-resolution coronal reformatted CT scans and classified into four morphological types per the Sagar classification. Type I canals , exhibiting non-protrusive morphology, were the most prevalent, comprising 60% of the sample. This aligns with foundational studies by Delano et al. (1) and Itagi et al. (2) , which documented a 76% prevalence of Type I —indicating this configuration as an anatomical baseline. However, increased frequencies of Type III (13.3%) and Type IV (12%) morphologies compared to prior reports reflect substantial inter-population diversity. Notably, Type III canals , defined by more than 50% protrusion into the sphenoid sinus, pose heightened surgical risks due to their spatial intrusion into sinus cavities and reduced bony insulation. This nuanced classification, which distinguishes Type II (less than 50% protrusion) and Type III (greater than 50%) , offers a more refined approach to risk assessment. Previous literature, including work by Itagi RM et al. (2) , has emphasized Type III ONCs as anatomically precarious—a finding reaffirmed by this study. Demographic Profile and Comparative Trends The cohort primarily consisted of individuals aged 21–40 years , with a mean age of 34.46 ± 11.12 years , and a female majority ( 67% ). These demographics align closely with other Indian studies such as those by Ravindra BN (3) and Dahal P et al. (4) , reinforcing regional relevance and generalizability. A comparative review of ONC distributions across studies revealed variability in the prevalence of higher-risk types, underscoring the influence of ethnicity, imaging protocols, and sample size on anatomical data (TABLE 5). Structural Vulnerability: Dehiscence and Pneumatization Structural variation of the optic canal wall significantly affects the optic nerve's protection. Bony dehiscence , defined as thinning or absence of the lamina cribrosa, was observed in 16% of cases—consistent with Itagi RM et al. (2) (17.75%) , but higher than reports by Aliu et al. (5) (7.74%) and Santhana Lakshmi R et al. (6) (2.15%) . Type III ONCs were most vulnerable , showing a striking 50% dehiscence rate , while Type II followed at 25% . This trend confirms the direct correlation between protrusive canal morphology and compromised bony coverage. Similar findings were reported by DeLano et al. (1) , who observed dehiscence in all Type III cases, and by Itagi RM et al. (2) , with 64.3% dehiscence in the same group. Concurrent evaluation of anterior clinoid process pneumatization (ACP) revealed its presence in 31.75% of individuals—a figure consistent with Ravindran BN et al. (3) (25.18%) and Kaya et al. (7) (21.15%) , and within the global range of 4% to 45% . ACP pneumatization amplifies surgical risk when accompanied by canal dehiscence, as the optic nerve may be directly exposed to the sphenoid sinus, creating a corridor for surgical or inflammatory insult. Notably, Type III ONCs again ranked highest , with 68.3% incidence of ACP pneumatization , supporting the theory that this morphology is associated with multi-vector vulnerabilities. Onodi Cells and Spheno-Ethmoidal Variants Anatomical variants such as Onodi cells —posterior ethmoidal air cells that lie adjacent to the optic canal—further complicate surgical planning. Their prevalence in this study was 32.7% , substantially higher than figures reported by Kaya et al. (7) (14%) and Aliu et al. (5) (7.74%) (TABLE 6). These cells can mask or distort the optic canal’s true location, increasing the probability of inadvertent optic nerve trauma. Implications for Surgical Practice The convergence of these anatomical findings suggests that Type III ONCs represent the highest-risk morphology due to their protrusive trajectory, frequent dehiscence, and coexistent ACP pneumatization. Surgeons operating in the paranasal and skull base regions must incorporate detailed CT-based mapping of ONC morphology into preoperative workflows. Identification of high-risk configurations, particularly in the presence of Onodi cells and pneumatized ACPs, is essential to avoid devastating complications such as optic nerve injury , retrobulbar hemorrhage , and CSF leak . These results support a paradigm shift toward individualized surgical planning , moving beyond generic anatomical expectations to population-specific and morphotype-informed intervention strategies. Further studies integrating clinical outcomes and longitudinal follow-up will strengthen the translational relevance of morphometric classifications and reinforce the role of preoperative imaging in procedural safety TABLE 5 : COMPARISON OF OPTIC NERVE TYPES WITH PREVIOUS STUDIES STUDY TYPE I TYPE II TYPE III TYPE IV Current study 60% 14.7% 13.3% 12% Itagi RM et al (2) 60% 15% 14% 11% Delano et al (1) 76% 15% 6% 3% Braggs et al (8) 61.8% 17.8% 7.6% 12.8% Santhana Lakshmi R et al (6) 65.8% 29.8% 1.8% 2.6% Ravindra BN Devika C (3) 83.33% 8.87% 12.1% 21.78% Bavin I B et al (9) 62.6% 18.6% 9.6% 9.6% Lakhani M et al (10) 55.93% 26.85% 11.1% 6.11% Hesoka G et al (11) 55.9% 14.7% 23.5% 5.9% Dahal P et al (4) 76.6% 24.5% 12.3% 14.4% TABLE 6 : PREVALENCE OF ONODI CELLS, OPTIC NERVE DEHISCENCE AND PNEUMATISATION OF ANTERIOR CLINOID PROCESS AMONG DIFFERENT STUDIES ONODI CELLS OPTIC NERVE DEHISCENCE PNEUMATISATION OF ANTERIOR CLINOID PROCESS Current study 22.7% 16% 21.3% Kaya et al 14% (7) 11,7% 25.1% Driben 8% to 14% (12) 7.74% 21.1% Itagi RM et al 11% (2) 2.1% 15% Lupascu M et al 18% (13) 17.5% 4% CONCLUSION This study underscores the critical importance of individualized anatomical assessment in endoscopic sinus and skull base surgery. The classification of optic nerve canal (ONC) morphology—particularly the identification of Type III variants—serves as a cornerstone for preoperative risk stratification. Type III ONCs demonstrate significantly higher rates of bony dehiscence (50%), anterior clinoid process pneumatization (68.3%), and Onodi cell association (32.7%), confirming their heightened vulnerability to surgical insult. By integrating morphometric categorization with assessment of ethmoidal variants and pneumatization patterns, surgical teams can move toward a paradigm of precision-guided intervention. This morphotype-informed approach is imperative to reduce the incidence of optic nerve injury and other serious complications. Future research should aim to couple anatomical findings with clinical outcomes to further validate and refine these classifications for broader translational impact. Declarations Ethics approval The study protocol received approval from the Institutional Ethics Committee of GMCH, Sector 32, Chandigarh on 09/08/23 under the letter Reference number GMCH IEC 2023/57. Approval was obtained from a different institution in view of no affiliated ethics committee in the parent institution. Consent to participate Informed written consent to participate in the study was obtained from all subjects (or their parent or legal guardian in the case of children under 16) to participate in the study before participation. Consent for publication Informed written consent for publication of the study was taken from the participants whose details, age , gender, diagnosis and images are included in the study. Availability of data and material The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare that they have no competing interests. Funding The study involves use of resources under the instituition. No financial funding was involved. Authors' contributions MW guided and proposed the original idea and domain of the research. SS executed and collected the data in the study alongside patient allotment , data collection, organisation and processing. SB guided and monitored the progression of the research. HS provided all the radiological provisions required for the procedure. SK compiled and edited the research for paper submission. References DeLano MC, Fun FY, Zinreich SJ. Relationship of the optic nerve to the posterior paranasal sinuses: a CT anatomic study. AJNR Am J Neuroradiol. 1996;17(4):669–75. Itagi RM, Adiga CP, Kalenahali K, Goolahally, Gyanchandani M. Optic nerve canal relation to posterior paranasal sinuses in Indian ethnics: Review and objective classification. J Clin Diagn Res. 2017;11(4):TC01–TC03. Ravindra BN, Devika C. Evaluation of optic nerve variations in relation to posterior paranasal sinuses among study population of Mandya District of Karnataka State. Int J Radiol Diagn Imaging. 2020;3(3):16–20. Dahal P, Parajuli S, Pradhan P, Maharjan S, Adhikari G, Tamang OY, Upadhyaya RP, Dawadi K, Shrestha A. Evaluation of variations of optic nerve course in relation to posterior paranasal sinuses in MDCT in a tertiary care center of Nepal: a retrospective cross-section study. Ann Med Surg. 2024;86(3):1309–14. Aliu A, Yunusa GH. Evaluation of the clinico-anatomical relationships between Onodi cells, optic nerve, and the sphenoid sinus, using tomographic imaging. Afr J Neurol Sci. 2020;39(2) Santhana Lakshmi R, Gugapriya TS, Vinay Kumar N, Guru TA. Positional variation of optic nerve in relation to sphenoid sinuses and its association with pneumatisation of anterior clinoid process: a radiological study. J Evid Based Med Healthc. 2015;2(32):4719–28. Kaya M, Çankal F, Gumusok M, Apaydin N, Tekdemir I. Role of anatomic variations of paranasal sinuses on the prevalence of sinusitis: Computed tomography findings of 350 patients. Niger J Clin Pract. 2017;20(11):1481–8. doi:10.4103/njcp.njcp_199_16. PMID: 29303136. Braggs A, Krishna KS. CT study of relationship of optic nerve to posterior paranasal sinuses. Int J Contemp Med Surg Radiol. 2018;3(4):D71–D73. Bavin IB, Nair MRB, Aneesh MK, George DA. Study on the optic nerve variations in relation to posterior paranasal sinuses using CT in tertiary care centre. Int J Med Sci Diagn Res. 2021;5(2) Lakhani M, Ali M, Sadiq M, Hassan N. Analysis of optic nerve types in relation to posterior paranasal sinuses: a computed tomographic (CT) study [Online]. Ann ASH KM&DC. 2017;22:249–54. Heskova G, Mellova Y, Holomanova A, Vybohova D, Kunertova L, Marcekova M, Mello M. Assessment of the relation of the optic nerve to the posterior ethmoid and sphenoid sinuses by computed tomography. Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2009;153(2):149–52. Driben JS, Bolger WE, Robles HA, Cable B, Zinreich SJ. The reliability of computerized tomographic detection of the Onodi (sphenoethmoid) cell. Am J Rhinol. 1998;12(2):105–12. doi:10.2500/105065898781390325. Lupascu M, Comsa Gh, Zainea V. Anatomical variations of the sphenoid sinus: a study of 200 cases. ARS Medica Tomitana. 2014;20(2):65–71. doi:10.2478/arsm-2014-0011. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7654380","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":549399545,"identity":"ba37d56c-138a-4e99-9490-2ae834728157","order_by":0,"name":"Dr. MANWINDER 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06:52:51","extension":"xml","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":66924,"visible":true,"origin":"","legend":"","description":"","filename":"0ce6ec8495e14d1c896dfeecf79a93c31structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7654380/v1/38e6077d8a795d2394528d23.xml"},{"id":96966671,"identity":"5c4636c1-ad7f-4ed5-8e5c-dd9663bd1d0f","added_by":"auto","created_at":"2025-11-28 06:52:51","extension":"html","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":75654,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7654380/v1/8ba92444fce6646d1eb43253.html"},{"id":96966662,"identity":"ab657200-097a-4a90-8eda-6b3703e980e6","added_by":"auto","created_at":"2025-11-28 06:52:51","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":502160,"visible":true,"origin":"","legend":"\u003cp\u003eA Coronal CT scan film showing optic nerve on left side (white arrow).\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7654380/v1/de44403a2541fa8f1f7da95e.png"},{"id":96966666,"identity":"018e5323-1c66-4a29-bedd-fb5a1836ff82","added_by":"auto","created_at":"2025-11-28 06:52:51","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":401868,"visible":true,"origin":"","legend":"\u003cp\u003eBilateral Type I ONC (right image) and bilateral Type II ONC (left image).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7654380/v1/1564e93894bc6add2c2535e5.png"},{"id":97138299,"identity":"c0ecbe5c-7a32-4ca0-8037-d43f979e41e7","added_by":"auto","created_at":"2025-12-01 09:58:45","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":125571,"visible":true,"origin":"","legend":"\u003cp\u003eRight Type III ONC\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7654380/v1/4ce44c02c1c698aeb7ad820b.png"},{"id":96966670,"identity":"ddef5009-95a4-47d7-ac15-cd7f21df7b8c","added_by":"auto","created_at":"2025-11-28 06:52:51","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":137309,"visible":true,"origin":"","legend":"\u003cp\u003eRight Type IV ONC (Onodi cell)\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7654380/v1/9800615443104e146e31a810.png"},{"id":98428898,"identity":"0f46563d-0a7c-49ce-af32-906dffeda480","added_by":"auto","created_at":"2025-12-17 16:42:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2921886,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7654380/v1/52d56802-c0c5-4d9f-8e54-fd216817be69.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eOptic Nerve Canal Variations and Their Surgical Implications: A Ct-based Study Using the Sagar Classification\u003c/p\u003e","fulltext":[{"header":"BACKGROUND","content":"\u003cp\u003eThe anatomical relationship between the optic nerve (ON) and the posterior paranasal sinuses\u0026mdash;particularly the posterior ethmoid and sphenoid sinuses\u0026mdash;is known to vary significantly. While the optic nerve canal (ONC) typically lies superolateral to the sphenoid sinus, it can occasionally protrude into or course through it entirely (shown in \u003cstrong\u003eFigure 1\u003c/strong\u003e) . In such cases, the nerve may be shielded only by a thin bone layer or mucosa, increasing its susceptibility to injury, especially when the bony wall is dehiscent or the sinus is extensively pneumatized.\u003c/p\u003e\n\u003cp\u003eA key variant of surgical relevance is the Onodi cell, a posterior ethmoidal air cell that may extend laterally and superiorly, sometimes enveloping the optic nerve. The proximity of this cell to vital structures\u0026mdash;including the optic chiasma, pituitary gland, olfactory tract, and cranial fossae\u0026mdash;makes accurate anatomical mapping essential prior to endoscopic sinus procedures.\u003c/p\u003e\n\u003cp\u003eThe anterior wall of the sphenoid sinus commonly contains the sinus ostium and connects to the ethmoid and vomer bones medially, and to the lateral ethmoid mass bilaterally. Onodi cells can displace this wall in multiple directions, complicating the anatomy. The thin lateral walls of the sphenoid sinus, which contain critical structures such as the internal carotid artery (ICA), ON, and cavernous sinus, are divided into orbital and cranial zones.\u003c/p\u003e\n\u003cp\u003eDue to the diversity in sphenoid and ethmoid sinus pneumatization, preoperative awareness of these variations is vital. Delano et al. (1996) proposed a classification system to clarify ON-sinus relationships, which was later refined as the \u0026ldquo;Sagar classification\u0026rdquo; in 2017 for improved surgical relevance.\u003c/p\u003e\n\u003cp\u003eThis study aims to evaluate the relationship between the optic nerve and the posterior paranasal sinuses through nasal endoscopy and non-contrast CT imaging (NCCT nose and PNS), using the Sagar classification as a framework. By identifying anatomical patterns, the research seeks to support safer surgical planning and reduce the risk of optic nerve injury during endoscopic interventions.\u003c/p\u003e"},{"header":"MATERIALS AND METHODS","content":"\u003cp\u003eStudy Design and Setting\u003c/p\u003e\n\u003cp\u003eThis prospective observational study was conducted over a 12-month period within the Departments of Otorhinolaryngology and Radiology at Government Multispeciality Hospital, Sector 16, Chandigarh.\u003c/p\u003e\n\u003cp\u003eParticipants\u003c/p\u003e\n\u003cp\u003eAdults (18\u0026ndash;75 years) presenting to the ENT outpatient department with signs and symptoms consistent with chronic rhinosinusitis (CRS) were enrolled. CRS diagnosis adhered to EPOS 2020 criteria, requiring \u0026ge;2 symptoms lasting at least 12 weeks\u0026mdash;major (nasal obstruction, nasal discharge) or minor (facial pain/pressure, hyposmia)\u0026mdash;plus endoscopic or CT evidence of mucosal pathology.\u003c/p\u003e\n\u003cp\u003eInclusion criteria comprised: \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Age between 18 and 75 years \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Endoscopic findings of deviated nasal septum, septal spur, turbinate hypertrophy, or concha bullosa \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Willingness to undergo CT imaging \u0026nbsp;\u003c/p\u003e\n\u003cp\u003eExclusion criteria comprised: \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Age \u0026lt;18 years \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Congenital craniofacial anomalies \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Sinonasal tumors or prior sinonasal surgery \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Acute infection with nasal polyposis \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Contraindications to ionizing radiation or significant comorbidities\u003c/p\u003e\n\u003cp\u003eSample Size and Sampling\u003c/p\u003e\n\u003cp\u003eSeventy-five CRS patients were recruited via simple random sampling. Each participant underwent non-contrast CT scanning of the paranasal sinuses.\u003c/p\u003e\n\u003cp\u003eEthical Considerations\u003c/p\u003e\n\u003cp\u003eThe study protocol received approval from the Institutional Review Board of GMCH, Sector 32, Chandigarh. Written informed consent was obtained from all subjects before participation.\u003c/p\u003e\n\u003cp\u003eExaminer Training and Calibration\u003c/p\u003e\n\u003cp\u003eThe radiologist underwent structured training on paranasal sinus anatomy and the Sagar classification of the optic nerve canal. Under expert supervision, the examiner interpreted CT scans in five pilot cases; intraobserver variability remained below 10%.\u003c/p\u003e\n\u003cp\u003eData Collection and Variables\u003c/p\u003e\n\u003cp\u003e- Demographics: age, gender \u0026nbsp;\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Radiological parameters (via CT): \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Anatomic variants (Onodi cells, pneumatisation of anterior clinoid process) \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Optic nerve canal dehiscence \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Optic nerve canal classification relative to the sphenoid and posterior ethmoid sinuses (Sagar classification)(TABLE 1)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTABLE 1\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"593\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE OF ONC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 443px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNUMBER OF CANALS\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eBONY DEHISCENCE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 443px;\"\u003e\n \u003cp\u003eNerve courses immediately close to sphenoid sinus wall without indentation\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 443px;\"\u003e\n \u003cp\u003eNerve courses close to the sphenoid sinus causing minimal indentation of the sinus wall\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE III\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 443px;\"\u003e\n \u003cp\u003eNerve courses through the sphenoid sinus with at least 50% of the nerve being surrounded by air\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE IV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 443px;\"\u003e\n \u003cp\u003eNerve courses immediately adjacent to sphenoid and \u0026nbsp;posterior ethmoid sinus ( presence of Onodi cell)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe above variations are depicted in \u003cstrong\u003eFigure 2,3 and 4.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCT Imaging Protocol\u003c/p\u003e\n\u003cp\u003e- Scanner: 16-slice Siemens Somatom Perspective \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Parameters: 120 kV, 300 mAs, 0.8 mm slice thickness, 15 cm field of view \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Acquisition: axial source images with coronal and sagittal reconstructions \u0026nbsp;\u003c/p\u003e\n\u003cp\u003e- Review: soft-tissue and bone windows assessed on multiplanar reformats to document paranasal sinus anatomy and optic nerve relationships.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cp\u003eThe present study analysed \u003cstrong\u003e150 optic nerve canals\u003c/strong\u003e (ONCs), obtained bilaterally from \u003cstrong\u003e75 individuals\u003c/strong\u003e, using computed tomography (CT) to classify canal morphology based on the \u003cstrong\u003eSagar classification\u003c/strong\u003e. The distribution, anatomical variations, and structural vulnerabilities associated with each ONC type were evaluated with respect to \u003cstrong\u003ebony dehiscence\u003c/strong\u003e and \u003cstrong\u003epneumatization of the anterior clinoid process (PAC)\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMorphological Classification of ONCs\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe ONCs were categorized into four types\u0026mdash;Type I to Type IV\u0026mdash;based on their morphological characteristics. Of the 150 canals studied(TABLE 2):\u003c/p\u003e\n\u003cul class=\"decimal_type\"\u003e\n \u003cli\u003e\u003cstrong\u003eType I\u003c/strong\u003e was the most prevalent, comprising \u003cstrong\u003e60%\u003c/strong\u003e of the sample (N=90), with a near-symmetrical distribution between right (29.3%) and left (30.7%) canals.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType II\u003c/strong\u003e represented \u003cstrong\u003e14.7%\u003c/strong\u003e (N=22) of canals, with slightly higher occurrence on the right side (9.4%) than the left (5.3%).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType III\u003c/strong\u003e accounted for \u003cstrong\u003e13.3%\u003c/strong\u003e (N=20), equally distributed across both sides.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType IV\u003c/strong\u003e, the least common, comprised \u003cstrong\u003e12%\u003c/strong\u003e (N=18), with marginal left-sided predominance (6.7% vs. 5.3%).\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe results demonstrate \u003cstrong\u003eType I morphology as the anatomical norm\u003c/strong\u003e, with Types II\u0026ndash;IV displaying greater variability and reduced prevalence.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTABLE 2 : OPTIC NERVE CANAL TYPES DISTRIBUTION OF THE PATIENTS BASED ON SAGAR CLASSIFICATION ON CT SCAN \u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"626\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE OF ONC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eRIGHT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eLEFT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 179px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTOTAL\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eTYPE I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e29.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e30.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eTYPE II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e9.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e5.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e14.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eTYPE III\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e5.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e13.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003eTYPE IV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e5.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e6.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 89px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003ePrevalence of Bony Dehiscence\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe integrity of the bony canal wall was assessed to identify cases of \u003cstrong\u003ebony dehiscence\u003c/strong\u003e, which may indicate structural vulnerability or pathological exposure of the optic nerve(TABLE 3):\u003c/p\u003e\n\u003cul class=\"decimal_type\"\u003e\n \u003cli\u003e\u003cstrong\u003eType III\u003c/strong\u003e canals showed the highest prevalence of dehiscence at \u003cstrong\u003e50%\u003c/strong\u003e (10 out of 20 canals).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType II\u003c/strong\u003e canals displayed a moderate rate of \u003cstrong\u003e25%\u003c/strong\u003e (5 out of 22).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType IV\u003c/strong\u003e had a dehiscence rate of \u003cstrong\u003e16.7%\u003c/strong\u003e (3 out of 18).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType I\u003c/strong\u003e demonstrated the lowest rate, with \u003cstrong\u003eonly 8.3%\u003c/strong\u003e (7 out of 90) affected.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe findings underscore a strong association between \u003cstrong\u003eType III morphology and increased susceptibility to bony dehiscence\u003c/strong\u003e, implying a structurally compromised canal wall in nearly half of these cases.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTABLE 3 : PREVALENCE OF BONY DEHISCENCE IN RESPECT TO ONC TYPES BASED ON CT SCAN\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"593\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE OF ONC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 254px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNUMBER OF CANALS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 188px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBONY DEHISCENCE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e8.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e14.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE III\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e13.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE IV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e16.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003ePneumatization of the Anterior Clinoid Process (PAC)\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePneumatization of the anterior clinoid process, a variant anatomical feature with potential surgical implications, was assessed across ONC types (TABLE 4):\u003c/p\u003e\n\u003cul class=\"decimal_type\"\u003e\n \u003cli\u003e\u003cstrong\u003eType III\u003c/strong\u003e again emerged as the most susceptible, with \u003cstrong\u003e68.8%\u003c/strong\u003e (11 out of 16 evaluated canals) showing PAC.\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType II\u003c/strong\u003e presented PAC in \u003cstrong\u003e18.7%\u003c/strong\u003e of cases (3 out of 16 canals).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType IV\u003c/strong\u003e exhibited PAC in \u003cstrong\u003e12.5%\u003c/strong\u003e of canals (2 out of 16).\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eType I\u003c/strong\u003e showed complete absence of PAC (\u003cstrong\u003e0%\u003c/strong\u003e), indicating a consistently non-pneumatized structure.\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThese results reveal a significant correlation between \u003cstrong\u003eType III ONC morphology and PAC\u003c/strong\u003e, suggesting that this anatomical variant may serve as a predictive marker for complex canal anatomy.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTABLE 4: PREVALENCE OF PNEUMATISATION OF ANTERIOR CLINOID IN RESPECT TO ONC TYPES BASED ON CT SCAN\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"593\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE OF ONC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 254px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eNUMBER OF CANALS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" valign=\"top\" style=\"width: 188px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePNEUMATISATION OF ANTERIOR CLINOID PROCESS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eN\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e%\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE I\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE II\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e22\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e14.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e18,7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE III\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e13.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e68.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003eTYPE IV\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 151px;\"\u003e\n \u003cp\u003e12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 75px;\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e16.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eEndoscopic sinus and skull base surgeries necessitate precise anatomical knowledge due to the intimate relationship between the paranasal sinuses and critical neurovascular structures such as the optic nerve and internal carotid artery. Variations in optic canal morphology, pneumatization of surrounding bone, and the presence of ethmoidal cell variants substantially influence surgical access and risk profiles.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMorphological Spectrum and Clinical Implications\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the current study, 150 ONCs were evaluated using high-resolution coronal reformatted CT scans and classified into four morphological types per the Sagar classification. \u003cstrong\u003eType I canals\u003c/strong\u003e, exhibiting non-protrusive morphology, were the most prevalent, comprising \u003cstrong\u003e60%\u003c/strong\u003e of the sample. This aligns with foundational studies by \u003cstrong\u003eDelano et al. \u003csup\u003e(1)\u003c/sup\u003e\u003c/strong\u003e and \u003cstrong\u003eItagi et al. \u0026nbsp;\u003csup\u003e(2)\u003c/sup\u003e\u003c/strong\u003e, which documented a \u003cstrong\u003e76% prevalence of Type I\u003c/strong\u003e\u0026mdash;indicating this configuration as an anatomical baseline.\u003c/p\u003e\n\u003cp\u003eHowever, increased frequencies of \u003cstrong\u003eType III (13.3%)\u003c/strong\u003e and \u003cstrong\u003eType IV (12%)\u003c/strong\u003e morphologies compared to prior reports reflect substantial inter-population diversity. Notably, \u003cstrong\u003eType III canals\u003c/strong\u003e, defined by more than 50% protrusion into the sphenoid sinus, pose heightened surgical risks due to their spatial intrusion into sinus cavities and reduced bony insulation.\u003c/p\u003e\n\u003cp\u003eThis nuanced classification, which distinguishes \u003cstrong\u003eType II (less than 50% protrusion)\u003c/strong\u003e and \u003cstrong\u003eType III (greater than 50%)\u003c/strong\u003e, offers a more refined approach to risk assessment. Previous literature, including work by \u003cstrong\u003eItagi RM et al. \u003csup\u003e(2)\u003c/sup\u003e\u003c/strong\u003e, has emphasized Type III ONCs as anatomically precarious\u0026mdash;a finding reaffirmed by this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDemographic Profile and Comparative Trends\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe cohort primarily consisted of individuals aged \u003cstrong\u003e21\u0026ndash;40 years\u003c/strong\u003e, with a mean age of \u003cstrong\u003e34.46 \u0026plusmn; 11.12 years\u003c/strong\u003e, and a female majority (\u003cstrong\u003e67%\u003c/strong\u003e). These demographics align closely with other Indian studies such as those by \u003cstrong\u003eRavindra BN \u003csup\u003e(3)\u003c/sup\u003e\u003c/strong\u003e and \u003cstrong\u003eDahal P et al. \u003csup\u003e(4)\u0026nbsp;\u003c/sup\u003e\u003c/strong\u003e, reinforcing regional relevance and generalizability.\u003c/p\u003e\n\u003cp\u003eA comparative review of ONC distributions across studies revealed variability in the prevalence of higher-risk types, underscoring the influence of ethnicity, imaging protocols, and sample size on anatomical data (TABLE 5).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStructural Vulnerability: Dehiscence and Pneumatization\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStructural variation of the optic canal wall significantly affects the optic nerve\u0026apos;s protection. \u003cstrong\u003eBony dehiscence\u003c/strong\u003e, defined as thinning or absence of the lamina cribrosa, was observed in \u003cstrong\u003e16%\u003c/strong\u003e of cases\u0026mdash;consistent with \u003cstrong\u003eItagi RM et al. \u003csup\u003e(2)\u003c/sup\u003e (17.75%)\u003c/strong\u003e, but higher than reports by \u003cstrong\u003eAliu et al. \u003csup\u003e(5)\u003c/sup\u003e (7.74%)\u003c/strong\u003e and \u003cstrong\u003eSanthana\u003c/strong\u003e \u003cstrong\u003eLakshmi R et al. \u003csup\u003e(6)\u003c/sup\u003e (2.15%)\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eType III ONCs were most vulnerable\u003c/strong\u003e, showing a striking \u003cstrong\u003e50% dehiscence rate\u003c/strong\u003e, while \u003cstrong\u003eType II\u003c/strong\u003e followed at \u003cstrong\u003e25%\u003c/strong\u003e. This trend confirms the direct correlation between protrusive canal morphology and compromised bony coverage. Similar findings were reported by \u003cstrong\u003eDeLano et al.\u003csup\u003e(1)\u003c/sup\u003e\u003c/strong\u003e, who observed dehiscence in all Type III cases, and by \u003cstrong\u003eItagi RM et al. \u003csup\u003e(2)\u003c/sup\u003e\u003c/strong\u003e, with \u003cstrong\u003e64.3% dehiscence\u003c/strong\u003e in the same group.\u003c/p\u003e\n\u003cp\u003eConcurrent evaluation of \u003cstrong\u003eanterior clinoid process pneumatization (ACP)\u003c/strong\u003e revealed its presence in \u003cstrong\u003e31.75%\u003c/strong\u003e of individuals\u0026mdash;a figure consistent with \u003cstrong\u003eRavindran BN et al. \u003csup\u003e(3)\u003c/sup\u003e (25.18%)\u003c/strong\u003e and \u003cstrong\u003eKaya et al. \u003csup\u003e(7)\u003c/sup\u003e (21.15%)\u003c/strong\u003e, and within the global range of \u003cstrong\u003e4% to 45%\u003c/strong\u003e. ACP pneumatization amplifies surgical risk when accompanied by canal dehiscence, as the optic nerve may be directly exposed to the sphenoid sinus, creating a corridor for surgical or inflammatory insult.\u003c/p\u003e\n\u003cp\u003eNotably, \u003cstrong\u003eType III ONCs again ranked highest\u003c/strong\u003e, with \u003cstrong\u003e68.3% incidence of ACP pneumatization\u003c/strong\u003e, supporting the theory that this morphology is associated with multi-vector vulnerabilities.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOnodi Cells and Spheno-Ethmoidal Variants\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnatomical variants such as \u003cstrong\u003eOnodi cells\u003c/strong\u003e\u0026mdash;posterior ethmoidal air cells that lie adjacent to the optic canal\u0026mdash;further complicate surgical planning. Their prevalence in this study was \u003cstrong\u003e32.7%\u003c/strong\u003e, substantially higher than figures reported by \u003cstrong\u003eKaya et al. \u003csup\u003e(7)\u003c/sup\u003e (14%)\u003c/strong\u003e and \u003cstrong\u003eAliu et al. \u003csup\u003e(5)\u003c/sup\u003e (7.74%) (TABLE 6).\u003c/strong\u003e These cells can mask or distort the optic canal\u0026rsquo;s true location, increasing the probability of inadvertent optic nerve trauma.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eImplications for Surgical Practice\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe convergence of these anatomical findings suggests that \u003cstrong\u003eType III ONCs\u003c/strong\u003e represent the highest-risk morphology due to their protrusive trajectory, frequent dehiscence, and coexistent ACP pneumatization. Surgeons operating in the paranasal and skull base regions must incorporate detailed CT-based mapping of ONC morphology into preoperative workflows. Identification of high-risk configurations, particularly in the presence of Onodi cells and pneumatized ACPs, is essential to avoid devastating complications such as \u003cstrong\u003eoptic nerve injury\u003c/strong\u003e, \u003cstrong\u003eretrobulbar hemorrhage\u003c/strong\u003e, and \u003cstrong\u003eCSF leak\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003eThese results support a paradigm shift toward \u003cstrong\u003eindividualized surgical planning\u003c/strong\u003e, moving beyond generic anatomical expectations to population-specific and morphotype-informed intervention strategies. Further studies integrating clinical outcomes and longitudinal follow-up will strengthen the translational relevance of morphometric classifications and reinforce the role of preoperative imaging in procedural safety\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTABLE 5 : COMPARISON OF OPTIC NERVE TYPES WITH PREVIOUS STUDIES\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"623\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSTUDY\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE I\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE II\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE III\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTYPE IV\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eCurrent study\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e60%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e14.7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e13.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e12%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eItagi RM et al\u003csup\u003e(2)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e60%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e15%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e14%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e11%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eDelano et al\u003csup\u003e(1)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e76%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e15%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e3%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eBraggs et al\u003csup\u003e(8)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e61.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e17.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e7.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e12.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eSanthana Lakshmi R et al\u003csup\u003e(6)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e65.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e29.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e1.8%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e2.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eRavindra BN Devika C\u003csup\u003e(3)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e83.33%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e8.87%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e12.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e21.78%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eBavin I B et al\u003csup\u003e(9)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e62.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e18.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e9.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e9.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eLakhani M et al\u003csup\u003e(10)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e55.93%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e26.85%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e11.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e6.11%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eHesoka G et al\u003csup\u003e(11)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e55.9%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e14.7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e23.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e5.9%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 132px;\"\u003e\n \u003cp\u003eDahal P et al\u003csup\u003e(4)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 117px;\"\u003e\n \u003cp\u003e76.6%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e24.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e12.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 125px;\"\u003e\n \u003cp\u003e14.4%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTABLE 6 : PREVALENCE OF ONODI CELLS, OPTIC NERVE DEHISCENCE AND PNEUMATISATION OF ANTERIOR CLINOID PROCESS AMONG DIFFERENT STUDIES\u0026nbsp;\u003c/strong\u003e\u0026nbsp;\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"623\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eONODI CELLS\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eOPTIC NERVE DEHISCENCE\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePNEUMATISATION OF ANTERIOR CLINOID PROCESS\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eCurrent study 22.7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e16%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e21.3%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eKaya et al 14% \u003csup\u003e(7)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e11,7%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e25.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eDriben 8% to 14% \u003csup\u003e(12)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e7.74%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e21.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eItagi RM et al 11% \u003csup\u003e(2)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e2.1%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e15%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003eLupascu M et al 18% \u003csup\u003e(13)\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e17.5%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 208px;\"\u003e\n \u003cp\u003e4%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eThis study underscores the critical importance of individualized anatomical assessment in endoscopic sinus and skull base surgery. The classification of optic nerve canal (ONC) morphology\u0026mdash;particularly the identification of Type III variants\u0026mdash;serves as a cornerstone for preoperative risk stratification. Type III ONCs demonstrate significantly higher rates of bony dehiscence (50%), anterior clinoid process pneumatization (68.3%), and Onodi cell association (32.7%), confirming their heightened vulnerability to surgical insult.\u003c/p\u003e\u003cp\u003eBy integrating morphometric categorization with assessment of ethmoidal variants and pneumatization patterns, surgical teams can move toward a paradigm of precision-guided intervention. This morphotype-informed approach is imperative to reduce the incidence of optic nerve injury and other serious complications. Future research should aim to couple anatomical findings with clinical outcomes to further validate and refine these classifications for broader translational impact.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eEthics approval \u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe study protocol received approval from the Institutional Ethics Committee of GMCH, Sector 32, Chandigarh on 09/08/23 under the letter Reference number GMCH IEC 2023/57. Approval was obtained from a different institution in view of no affiliated ethics committee in the parent institution.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u0026nbsp;Informed written consent to participate in the study was obtained from all subjects\u0026nbsp;\u0026nbsp;(or their parent or legal guardian in the case of children under 16)\u0026nbsp;\u0026nbsp;to participate in the study before participation.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eInformed written consent for publication of the study was taken from the participants whose details, age , gender, diagnosis and images are included in the study.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eAvailability of data and material\u0026nbsp;\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u0026nbsp;The authors declare that they have no competing interests.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe study involves use of resources under the instituition. No financial funding was involved.\u003c/p\u003e\n\u003cul\u003e\n \u003cli\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eMW guided and proposed the original idea and domain of the research. SS executed and collected the data in the study alongside patient allotment , data collection, organisation and processing. SB guided and monitored the progression of the research. HS provided all the radiological provisions required for the procedure. SK compiled and edited \u0026nbsp;the research for paper submission.\u003c/p\u003e"},{"header":"References","content":"\u003col start=\"1\" type=\"1\"\u003e\n \u003cli\u003eDeLano MC, Fun FY, Zinreich SJ. Relationship of the optic nerve to the posterior paranasal sinuses: a CT anatomic study. \u003cem\u003eAJNR Am J Neuroradiol.\u003c/em\u003e 1996;17(4):669\u0026ndash;75.\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"2\"\u003e\n \u003cli\u003eItagi RM, Adiga CP, Kalenahali K, Goolahally, Gyanchandani M. Optic nerve canal relation to posterior paranasal sinuses in Indian ethnics: Review and objective classification. \u003cem\u003eJ Clin Diagn Res.\u003c/em\u003e 2017;11(4):TC01\u0026ndash;TC03.\u003c/li\u003e\n\u003c/ol\u003e\n\u003col start=\"3\" type=\"1\"\u003e\n \u003cli\u003eRavindra BN, Devika C. Evaluation of optic nerve variations in relation to posterior paranasal sinuses among study population of Mandya District of Karnataka State. \u003cem\u003eInt J Radiol Diagn Imaging.\u003c/em\u003e 2020;3(3):16\u0026ndash;20.\u003c/li\u003e\n \u003cli\u003eDahal P, Parajuli S, Pradhan P, Maharjan S, Adhikari G, Tamang OY, Upadhyaya RP, Dawadi K, Shrestha A. Evaluation of variations of optic nerve course in relation to posterior paranasal sinuses in MDCT in a tertiary care center of Nepal: a retrospective cross-section study. \u003cem\u003eAnn Med Surg.\u003c/em\u003e 2024;86(3):1309\u0026ndash;14.\u003c/li\u003e\n \u003cli\u003eAliu A, Yunusa GH. Evaluation of the clinico-anatomical relationships between Onodi cells, optic nerve, and the sphenoid sinus, using tomographic imaging. \u003cem\u003eAfr J Neurol Sci.\u003c/em\u003e 2020;39(2)\u003c/li\u003e\n \u003cli\u003eSanthana Lakshmi R, Gugapriya TS, Vinay Kumar N, Guru TA. Positional variation of optic nerve in relation to sphenoid sinuses and its association with pneumatisation of anterior clinoid process: a radiological study. \u003cem\u003eJ Evid Based Med Healthc.\u003c/em\u003e 2015;2(32):4719\u0026ndash;28.\u003c/li\u003e\n \u003cli\u003eKaya M, \u0026Ccedil;ankal F, Gumusok M, Apaydin N, Tekdemir I. Role of anatomic variations of paranasal sinuses on the prevalence of sinusitis: Computed tomography findings of 350 patients. \u003cem\u003eNiger J Clin Pract.\u003c/em\u003e 2017;20(11):1481\u0026ndash;8. doi:10.4103/njcp.njcp_199_16. PMID: 29303136.\u003c/li\u003e\n \u003cli\u003eBraggs A, Krishna KS. CT study of relationship of optic nerve to posterior paranasal sinuses. \u003cem\u003eInt J Contemp Med Surg Radiol.\u003c/em\u003e 2018;3(4):D71\u0026ndash;D73.\u003c/li\u003e\n \u003cli\u003eBavin IB, Nair MRB, Aneesh MK, George DA. Study on the optic nerve variations in relation to posterior paranasal sinuses using CT in tertiary care centre. \u003cem\u003eInt J Med Sci Diagn Res.\u003c/em\u003e 2021;5(2)\u003c/li\u003e\n \u003cli\u003eLakhani M, Ali M, Sadiq M, Hassan N. Analysis of optic nerve types in relation to posterior paranasal sinuses: a computed tomographic (CT) study [Online]. \u003cem\u003eAnn ASH KM\u0026amp;DC.\u003c/em\u003e 2017;22:249\u0026ndash;54.\u003c/li\u003e\n \u003cli\u003eHeskova G, Mellova Y, Holomanova A, Vybohova D, Kunertova L, Marcekova M, Mello M. Assessment of the relation of the optic nerve to the posterior ethmoid and sphenoid sinuses by computed tomography. \u003cem\u003eBiomed Pap Med Fac Univ Palacky Olomouc Czech Repub.\u003c/em\u003e 2009;153(2):149\u0026ndash;52.\u003c/li\u003e\n \u003cli\u003eDriben JS, Bolger WE, Robles HA, Cable B, Zinreich SJ. The reliability of computerized tomographic detection of the Onodi (sphenoethmoid) cell. \u003cem\u003eAm J Rhinol.\u003c/em\u003e 1998;12(2):105\u0026ndash;12. doi:10.2500/105065898781390325.\u003c/li\u003e\n \u003cli\u003eLupascu M, Comsa Gh, Zainea V. Anatomical variations of the sphenoid sinus: a study of 200 cases. \u003cem\u003eARS Medica Tomitana.\u003c/em\u003e 2014;20(2):65\u0026ndash;71. doi:10.2478/arsm-2014-0011.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Optic nerve canal (ONC), CT imaging, Sagar classification, Endoscopic sinus surgery, Bony dehiscence, Anterior clinoid process pneumatization, Onodi cells, Chronic rhinosinusitis (CRS), Surgical anatomy","lastPublishedDoi":"10.21203/rs.3.rs-7654380/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7654380/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBACKGROUND:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAnatomical variations in the optic nerve canal (ONC) significantly influence surgical risk during endoscopic procedures involving the posterior paranasal sinuses. This study evaluates ONC morphology using the Sagar classification via high-resolution computed tomography (CT), with clinical emphasis on predicting surgical vulnerabilities.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMATERIALS AND METHODS:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA prospective observational study was conducted over 12 months at a tertiary hospital in North India involving 75 adult patients diagnosed with chronic rhinosinusitis (CRS) according to EPOS 2020 criteria. Bilateral ONCs (N=150) were categorized into four types using CT scans and assessed for bony dehiscence, anterior clinoid process (ACP) pneumatization, and presence of Onodi cells.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRESULTS:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eType I ONCs were predominant (60%), followed by Type II (14.7%), Type III (13.3%), and Type IV (12%). Type III ONCs had the highest prevalence of bony dehiscence (50%) and ACP pneumatization (68.8%), indicating increased anatomical vulnerability. Onodi cells were seen in 32.7% of cases, further complicating surgical access.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCONCLUSION:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDetailed CT evaluation of ONC morphology is essential for individualized surgical planning. Type III ONCs, with their high-risk anatomical profile, require particular attention in preoperative imaging due to elevated risk of optic nerve injury.\u003c/p\u003e","manuscriptTitle":"Optic Nerve Canal Variations and Their Surgical Implications: A Ct-based Study Using the Sagar Classification","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-11-28 06:52:46","doi":"10.21203/rs.3.rs-7654380/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"590818d2-13af-43d9-9a3f-95fb7cc4b2ca","owner":[],"postedDate":"November 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-12T11:39:14+00:00","versionOfRecord":[],"versionCreatedAt":"2025-11-28 06:52:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7654380","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7654380","identity":"rs-7654380","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}